Vascular disease involves damage that happens to the blood vessels in the body. Diseased blood vessels can become plugged with thrombus, plaque, clots, grumous material, and/or other unwanted matter (hereafter “obstructions”) that may ultimately lead to a condition known as ischemia. Ischemia refers to a substantial reduction or loss of blood flow to the brain or any other tissue that is being supplied by the blood vessel and can lead to permanent damage of the affected region. While vascular disease is most commonly associated with the formation of hard plaque and coronary artery disease in the heart, similar damage can happen to many other vessels in the body, such as the peripheral vessels and cerebral vessels, due to the buildup of obstructions, including hard plaque or softer thrombus/grumous material, within the lumen of an artery or vein.
A variety of vascular medical devices and procedures have been developed to treat diseased vessels. The current standard procedures include bypass surgery (where a new blood vessel is grafted around a narrowed or blocked artery) and several different types of non-surgical interventional vascular medical procedures, including angioplasty (a balloon on a catheter is inflated inside a narrowed or blocked portion of an artery in an attempt to push back the obstruction), lytic therapy (pharmaceutical agents are employed to chemically fragment the obstruction), stenting (a metal mesh tube is expanded against a narrowed or blocked portion of an artery to hold back the obstruction), and debulking techniques in the form of atherectomy (a high speed or high power mechanism is used to dislodge or mechanically abrade a hardened obstruction) or thrombectomy (a mechanism or infused fluid is used to dislodge/remove the obstruction). In each of these interventional vascular medical procedures, a thin, flexible guidewire is routed through the patient's vascular system to a desired treatment location and then a catheter, carrying a device appropriate for the given procedure, is tracked along the guidewire to the treatment location.
Although interventional vascular procedures avoid many of the complications involved in surgery, there is a possibility of complications if some of the obstruction breaks free and flows downstream in the blood vessel or into a connected blood vessel, potentially causing a stroke, a myocardial infarction (heart attack), or other tissue death. One solution to this potential complication is to use some kind of occlusive device or filtering device to block or screen the blood flowing downstream of the treatment location.
An example of a vascular filter is disclosed in U.S. Patent Application Publication No. 2002/0111648, published Aug. 15, 2002 by Richard S. Kusleika et al. (hereafter referenced as “the '648 publication”). The '648 publication discloses a collapsible medical device including a radially expandable body having proximal and distal sliders slidably attached to a mandrel (Abstract). The medical device is placed at a predetermined treatment site, such as a convenient location in a patient's vasculature positioned distally of an obstruction which will be treated with an angioplasty balloon or an atherectomy device (¶0066). At least one embodiment of the medical device of the '648 publication can be used to filter fluid which is passing through a vessel and also can either temporarily or permanently occlude the vessel. The medical device of the '648 publication, however, may cause undue mechanical trauma or irritation to a previously healthy portion of the blood vessel because of the remote deployment from the obstruction site. Moreover, temporary or permanent occlusion of the blood vessel may cause ischemia and/or additional clotting of stagnant blood, thus adding to any such damage already caused by the unwanted obstruction.